Citation and License

Nutrition Journal 2011, 10:7
doi:10.1186/1475-2891-10-7

Published: 19 January 2011

Abstract

Background

Rye products have been demonstrated to lower the acute insulin demand, induce a low
and prolonged blood glucose response (high Glycemic Profile, GP) and reduce subclinical
inflammation. These products may therefore contribute to a lowered risk of obesity,
type 2 diabetes and cardio vascular disease. The objective of the present paper was
to evaluate the mechanism for a reduced postprandial insulin demand with rye products,
and to explore possible appetite regulating properties.

Methods

10 healthy subjects were served breakfast meals (50 g of available starch) with endosperm-
or whole grain rye breads, with and without lactic acid, boiled whole grain rye- (RK)
or wheat (WK) kernels, or white wheat bread reference (WWB) in random order in a cross-over
design. Plasma concentrations of glucose, ghrelin, serum insulin, free fatty acids,
adiponectin, breath hydrogen excretion (H2), and subjective satiety was evaluated during the postprandial phase. 270 min after
the breakfast, an ad lib lunch buffet was served and the voluntary energy intake (EI)
was registered.

Results

All rye products and WK induced lower insulinemic indices (II) than WWB. A lower incremental
insulin peak following breakfast correlated with a lower EI at lunch (r = 0.38). A
low II was related to improved satiety in the early postprandial phase (fullness AUC
0-60 min, r = -0.36). RK induced a higher GP compared to WWB and WK. A higher GP was
related to a lowered desire to eat before lunch (AUC 210-270) and to a lower concentration of ghrelin in the late postprandial
phase after breakfast (270 min), r = -0.29 and -0.29), which in turn was related to
a lower voluntary EI (r = 0.43 and 0.33). The RK breakfast improved satiety in the
early postprandial phase (0-60 min) compared to WWB, and induced a lower EI at lunch
(-16%). A high content of indigestible carbohydrates in the breakfast products was
related to improved satiety (0-60 min, r = 0.68 for fullness), and a higher breath
H2 in the late postprandial phase (120-270 and 270-390 min, r = 0.46 and 0.70). High
H2 (AUC 120-270 min) also correlated with lower EI (r = -0.34).

Conclusions

Rye products, rich in indigestible carbohydrates, induce colonic fermentation already
post the breakfast meal, and lowers acute insulin responses. A high excretion of breath
H2 also correlated with a higher GP. Especially, rye kernels induced a high GP which
was associated with a 16% lowering of energy intake at a subsequent lunch meal. The
bulking effect of rye fiber, colonically derived fermentation metabolites, a high
GP and a low insulin response possibly all contributes to the benefits on glucose-
and appetite regulation seen in an acute and semi-acute perspective.